Maybe it would help if you actually posted more info. If it was working before and now it's not, then my first guess is that something has changed.

What has happened since it last worked? Maybe the config file is corrupted. Try creating a new directory and running a comlpetely default version to see if it still happens. Have you change Anti-virus or firewall settings recently or changed anything else at all. Unless you can give at least a few more details all you will get is guesses.

Maybe you just need to reformat and reinstall the OS, then install a new video card and that will sort it out

If you want to try an older version, you can download them from the same place you downloaded the version you already have. Just check the link in the first post of the SM forum.